You can pick up a steel paperclip with a bar magnet, and suddenly that paperclip can pick up another one—but as soon as you remove the magnet, the chain falls apart. This happens because there are two distinct types of magnets: permanent and induced. A permanent magnet produces its own magnetic field continuously. It has two fixed magnetic poles: a North-seeking pole and a South-seeking pole. These magnets retain their magnetism for a long time without needing an external field because they are made from magnetically hard materials, such as steel.
Only four specific magnetic materials can be magnetised or attracted to a magnet: iron, steel, cobalt, and nickel. When one of these unmagnetised materials is placed inside an external magnetic field, it becomes an induced magnet. This means it only has a magnetic field while it remains near the permanent magnet. Induced magnetism is highly temporary. Once the external magnetic field is removed, the material quickly loses most or all of its magnetism because it is typically made from a magnetically soft material, like pure iron. High-level explanations describe this process as the temporary alignment of internal magnetic domains.
Permanent magnets can either attract or repel each other depending on which poles are facing. However, a permanent magnet and an induced magnet will always experience a force of attraction. This happens because the permanent magnet induces a temporary pole in the part of the material closest to it. The induced pole is always the exact opposite of the permanent magnet's pole. Because opposite poles always attract, the magnetic material is pulled toward the permanent magnet, regardless of whether the North or South pole is used.
When asked to explain the difference in an exam, you must clearly distinguish how they behave and what they are made of.
| Feature | Permanent Magnet | Induced Magnet |
|---|---|---|
| Source of Field | Produces its own field continuously | Only has a field when inside an external magnetic field |
| Duration | Permanent (retains magnetism) | Temporary (loses magnetism when the external field is removed) |
| Forces | Can attract or repel other magnets | Always experiences a force of attraction to a permanent magnet |
| Poles | Fixed North and South poles | Temporary poles that depend on the external field |
| Material Type | Magnetically hard (e.g., steel) | Magnetically soft (e.g., iron) |
Students often incorrectly suggest an unmagnetised material can be repelled because it 'is magnetic'. Remember that unmagnetised magnetic materials never repel; only two permanent magnets can repel.
In explanation questions about attraction, examiners expect you to explicitly state that 'magnetism is induced' and 'the induced pole is opposite to the pole of the permanent magnet'.
Repulsion is the only valid test to prove that an unknown object is a permanent magnet. If it only attracts, it could just be an unmagnetised piece of iron or steel.
Permanent magnet
A magnet that produces its own magnetic field continuously and retains its magnetic properties for a long period.
Induced magnet
A piece of magnetic material that only becomes a magnet when it is placed in an external magnetic field.
Magnetic poles
The regions on a magnet (North and South) where the magnetic forces are at their strongest.
Magnetic materials
Materials that experience a force when placed in a magnetic field, specifically iron, steel, cobalt, and nickel.
Force of attraction
A pull force that draws objects together, which always occurs between a permanent magnet and a magnetic material.
Magnetically hard
A material that is difficult to magnetise but retains its magnetism once magnetised, making it ideal for permanent magnets.
Magnetically soft
A material that is easy to magnetise but loses its magnetism almost instantly when the external field is removed.
Magnetic domains
Small internal regions within a magnetic material where the magnetic fields of atoms are grouped together and aligned.
Put your knowledge into practice — try past paper questions for Physics
Permanent magnet
A magnet that produces its own magnetic field continuously and retains its magnetic properties for a long period.
Induced magnet
A piece of magnetic material that only becomes a magnet when it is placed in an external magnetic field.
Magnetic poles
The regions on a magnet (North and South) where the magnetic forces are at their strongest.
Magnetic materials
Materials that experience a force when placed in a magnetic field, specifically iron, steel, cobalt, and nickel.
Force of attraction
A pull force that draws objects together, which always occurs between a permanent magnet and a magnetic material.
Magnetically hard
A material that is difficult to magnetise but retains its magnetism once magnetised, making it ideal for permanent magnets.
Magnetically soft
A material that is easy to magnetise but loses its magnetism almost instantly when the external field is removed.
Magnetic domains
Small internal regions within a magnetic material where the magnetic fields of atoms are grouped together and aligned.